Method and apparatus for generating a query to an information system specified using natural language-like constructs

ABSTRACT

Computerized tools for modeling database designs and specifying queries of the data contained therein. Once it is determined that an information system needs to be created, the Fact Compiler of the present invention is invoked to create it. After creating the information system, the user creates a fact-tree as a prelude to generating queries to the system. After creating the fact-tree, the user verifies that it is correct using the Tree Interpreter of the present invention. Once the fact tree has been verified, the Query Mapper of the present invention is used to generate information system queries.

This application is a division of application Ser. No. 08/112,852, filed Aug. 25, 1993, now U.S. Pat. No. 5,495,604.

TECHNICAL FIELD

This invention relates to the creation of computer database systems and the querying of data contained therein. In particular, the invention relates to computerized tools for modeling database designs and specifying queries of the data contained therein.

BACKGROUND ART

Computerized relational databases are used to form information systems which model real world issues and are composed of objects, the relationships i.e., facts, between those objects and the constraints and rules which govern these relationships and objects. Objects are physical or logical entities, capable of being uniquely identified. In this respect, objects are said to be essentially noun-like. Facts define the manner in which objects interact with one another, and are essentially verbs or are verb-like. Constraints modify or constrain the inter-relationships between objects and facts, and as such are analogous to adverbs and pronouns. As the use of information systems increases and the design of such systems advance, so increases the complexity of the real world issues they are expected to accurately model.

In creating an information system, a user needs to accurately transform the real world model, also known as the external view of the data, to its actual physical implementation, using a particular database language on a particular computer system. This implementation is aim called the physical view. In order to realize the power inherent in relational databases, it must be made possible for someone with no computing background or education to be able to design and implement information management systems and query meaningful data from them without having to learn a specific computer language.

The physical view of an information system is expressed in one of a number of database design languages. Examples of database design languages well known to those skilled in the art include Structured Query Language (SQL) and Microsoft Access. These database design languages are well adapted to carry out the storage and subsequent retrieval of data stored therein, but the languages themselves are both unnatural and highly technology specific. This means that database design languages are not typically used or Understood by the end users of the information systems the languages model. The use of these design languages is a largely intuitive process practiced by database analysts who are familiar with the internal complexities of such languages.

The transformation of an information system from its external view to its physical view is time consuming, and at once formalized while remaining something of an art form. In order to assist database analysts in modeling data for information system design, several Computer Aided Software Engineering (CASE) tool sets have been developed, and are well known to those skilled in the art.

Prior art CASE tool sets were generally based upon entity-relationship modeling (ER). ER models, while providing a useful means of summarizing the main features of an application, are typically incapable of expressing many constraints and derivation rules that commonly occur in that application. An overview of ER-base tools may be found in Ovum (1992) and Reiner (1992) A state-of-the-art example is discussed in Czejdo et at. (IEEE Computer, Mar 1990, pp.26-37).

In order to capture much more of the detail of an application, object-role modelling (ORM), also known as fact-oriented modeling, was developed. Well known prior art versions of ORM include Natural-Language Information Analysis Method (NIAM), Binary-Relationship Modelling (BRM), Natural Object Role Modelling (NORM), and Predicator Set Model (PSM). One version of ORM, o Formal Object Role Modelling (FORM) is based on extensions to NIAM and has an associated language (FORML) with both graphical and textual forms (Halpin and Orlowska, 1992). FORM and FORML were developed in part by one of the inventors of the present invention.

The use of symbol-driven CASE tool sets provides a powerful instrument for conceptualizing the model of a given information system, but their use is not intuitively obvious to the untrained user. For such a user, being able to model information systems using a language with which the user is already facile is a more powerful approach. FORML provides the user with a natural language-like command set, and is thus readily learned.

Several CASE tool sets for object-role modeling exist. Among those known by persons skilled in the art are RIDL (Detroyer et at, 1988; Detroyer 1989; Nienhuys-Cheng 1990), GIST (Shoval et at, 1988) and IAST (Control Data, 1982). RIDL is currently marketed by Intellibase. These ORM-based CASE tool sets generally conform only to a binary-only version of ORM, although RIDL has recently added support for fact types of higher arity. In general, these systems are based upon the explicit "drawing" of symbols on diagram. Users of these tool sets typically specify their information systems by placing symbols directly on diagrams. In the typical CASE tool set, a different tool is used for each type of symbol used. The emphasis in these tool sets is on the notation of the symbols and what they mean, not the underlying semantics of the language upon which the notation rests.

An "optimal normal form" method for mapping from ORM to normalized relational tables was introduced in NIAM in the 1970's. This method ignored certain cases and provided a very incomplete specification of the methodology for constraint mapping. A significant extension of NIAM, capable of completely mapping any conceptual schema expressed in the graphic version of FORML to a redundancy-free, relational schema, was introduced as RMAP (Relational Mapping, Ritson and Halpin, 1992). RMAP differs from other mapping methods, such as RIDL-M, by enabling a wider variety of constraints; e.g., n-ary subset, equality, exclusion, closure and ring constraints.

Database professionals, using ORM-based CASE tool sets are markedly more productive than similar workers without them. A tool set which contains a mapping schema such as RMAP is even more powerful, and results in further productivity. FORML based tool sets which implement RMAP represent the current state of the art with respect to ORM-based tool sets. Given FORML's graphical and textual language forms, the potential exists to combine the power, flexibility and precision of ORM based CASE tool sets with the ease and rapidity of use of graphical user interfaces common in modem computer systems. This will have the effect not only of further increasing the productivity of CASE tool sets in the hands of computer professionals, but will place these powerful software engineering tools in the hands of heretofore naive users as well.

While prior art natural language CASE tools do fulfill some of the promise of their basic concept, they lack the power of the symbol driven systems to model complex databases with facility. Until the present invention, there existed no CASE tool set for database design which combined the power, flexibility and accuracy of ORM using natural language-like constructs with a graphical user interface to translate the natural language-like constructs into ORM symbology and automatically map the conceptual schema so formed into a relational schema for implementation on a number of SQL-like database languages. The present invention effects a six-fold reduction in the number of user operations necessary to draw symbols on ORM-based diagrams by allowing users to type information in an approximately natural language. Users can think about the semantics of information and not waste time laboring on symbol drawing, which dampens the semantic thought process.

In addition to the ER and ORM-based prior an tool sets previously discussed, there have been efforts by other workers to automate the process of database specification using different methodologies. Some of the more pertinent attempts are described below.

U.S. Pat. No. 4,688,196 to Thompson et. al. teaches a natural language interface generating system which allows a naive user to create and query a database based on a system of menu-driven interfaces. As the user addresses command words, in a natural language, to the interface generating system it provides a menu of words which could legally follow each word as it is input. The menu is provided by referencing pre-defined, resident files. Thompson calls these flies grammars and lexicons. The commands input by the user are translated by the system, which then provides an automatic interactive system to generate the required interface in the following manner. After the database is loaded in, the interface generating system poses a series of questions to the user's technical expert. In response to these questions, the user or his expert must identify which tables in the database are to be used; which attributes of particular tables are key attributes; what the various connections are between the various tables in the database and what natural language connecting phrases will describe those relations.

U.S. Pat. No. 4,939,689 to Davis et. al. teaches a system for the creation of database structures and subsequent querying of those structures by use of a text driven outliner system. The Davis system uses another form of resident dictionary table, which is again previously defined. In Davis, the user inputs a textual outline which defines the format of the database. This outline is then used to create data entry screens to facilitate data entry.

After creating database information systems (and assuming the data to populate those systems has been input), the information system must be accurately queried. Efforts by others skilled in the present art teach two broad strategies to enable the naive user to form queries.

The first prior art solution to the query generation problem is through the use of natural language parsers. This methodology takes a query which is input in a desired natural language such as English or Japanese, and parses the query into its component parts. Each component of the query is then used to form the translation of the original natural language query into a database language query. Until the present invention, this was typically accomplished by some form of resident database or dictionary file which translated the parsed command words and phrases into their respective equivalents in the database design language.

European Patent Application EP 0522591A2, filed 10 Jul., 1992 by Takanashi et. al., teaches a system typical of this "parse and look up" strategy, whereby a natural language query is entered and parsed into its constituent parts. The parser uses both a resident grammar table and a resident terminology dictionary to translate the meaning of individual command words and phrases into the database design language. The difficulty with fully implementing this solution is the richness and power i.e., the size and variable structure, of most natural languages. Each possible word and many phrases must have a corresponding entry in the resident tables to make the system truly utile. If this is not done, the power of the natural language interface is substantially weakened in that a command will not be understood by the system.

The cost, both monetary and in computer overhead, of creating and maintaining a large, full-time resident natural language interface to any substantial information system is prohibitive. Furthermore, end users are still required to know the types of questions and keywords the parser and resident dictionary files will understand. This is because the resident table methodology does not fully account for the relationships between data objects and the constraints on those objects. For example, if a user wants to know Mr. Smith's age, it is not sufficient to ask "How old is Smith ?" since Smith might be a person or the Smith Tower. Instead the user must type "How old is the person called Smith ?". As a result, the learning curve for using natural language parsers is still extremely high.

The second solution to the query generation problem in the prior art is through the use of query tools. Query tools are based on the physical structures of the database and not the information contained therein. Information can be broadly categorized as a set of interacting conceptual objects, i.e. things you want to store--e.g., Person, Address, etc. Facts are relationships between objects--e.g. a Person lives at an address. When information is stored in a database, it is represented as a set of physical structures, e.g. tables. Absent considerable database expertise on the part of an end user, the physical representation of the data is invariably unintelligible to him or her. To enable, therefore, such a naive user to query data based on the physical structure it is stored in will require a significant training effort to ensure understanding of these physical structures.

In formulating a query using either a natural language parser or a physical structure query tool, one final issue remains. The user can never be sure that the query which is ultimately formed by either process is actually phrased correctly. When querying physical structures, absent significant training, the naive user doesn't understand the manner in which the data was stored. When using a natural language parser, the same problem arises due to the ambiguity inherent in that natural language. If, for instance, a user asked "How old is Smith ?", and the computer answers "55", the answer may be for the person Smith, or the Smith Tower. This is reminiscent of the experience of a reporter who telegraphed Cary Grant's agent, asking about Mr. Grant's age. The reporter, sensitive to the cost per word of sending a telegraph, queried "HOW OLD CARY GRANT?". The actor, when the telegraph was inadvertently delivered to him, replied, again by telegraph, "OLD CARY GRANT JUST FINE". Clearly, unless the syntax of the query is correct, a naive user may retrieve an uncertain answer or an answer to an unintended query.

A common design feature of prior art CASE tools as previously discussed is the use of a pre-defined table or tables both to effect the translation of natural language inputs and to specify the exact nature of the data objects, facts and constraints as well as the interrelationships therebetween. As discussed, this methodology is costly, inefficient and not fully effective.

A further design feature of CASE tools currently in use for information system specification is their use of symbols instead of a natural language. A symbology-driven CASE tool set is at once imprecise and cumbersome, requiting several steps to perform the transformation from a chart of symbols to a database specification in a computer language.

There is therefore a need for apparatus that allows users to specify and create an information system using natural language or natural language-like commands, which will precisely specify the system's objects, facts and constraints without ambiguity or excessive overhead. This means should be capable of graphical depiction to define the interrelationships among the data elements in an unambiguous manner. The information used to create the system should be useable to define both the structure of the database itself as well as subsequent queries to that database once it is completed. There is a another need for a means for a naive user to be able to specify these queries to the system, again using natural language like commands which are not bound by previously entered definitions in a translation table. There is yet another need for a means for ensuring that any query which is created for the purpose of accessing the information system will, precisely and again without ambiguity, convey the user's intended question and return a correct, unambiguous answer.

DISCLOSURE OF INVENTION

The present invention provides a method and apparatus that allows users to:

1. Develop an information system description using a graphical user interface to a natural language-like computer language. One such language is FORML.

2. Specify the fact tree for query generation.

3. Check queries for semantic correctness.

4. Generate queries to the database system.

Once it has been determined that an information system needs to be created, the Fact Compiler of the present invention is invoked. The Compile function of the Fact Compiler enables a user to type in text, using a natural language-like computer language. One such language is FORML. The text is typed in a window provided by the system, and may contain objects (also referred to herein as nouns), facts (also referred to herein as fact types or sentences) and/or constraints. Using a translation function called "Drag and Drop over Diagram" and a graphical user interface, the user then drags the text from the entry window to the appropriate place over the ORM conceptual schema diagram of the Fact Compiler. The user then drops the text onto the diagram. The Fact Compiler validates the text entered and notifies the user of any errors encountered. During validation, the Fact Compiler first parses the text and creates an object list, a fact list and a constraint list in memory. Then the Fact Compiler iteratively compiles the text into the repository. The repository is essentially a "database of databases". Finally, the validated objects, facts and/or constraints are drawn in proper notation on the ORM conceptual schema diagram. At this point the information system specification may be considered complete.

After the information system has been created, the user may wish to check and/or edit the previously entered information. This is accomplished by using the Decompile function of the Fact Compiler. Decompile is essentially the reverse of the previously discussed Compile function, in that it takes an ORM conceptual schema diagram and returns a textual listing of the objects, facts and constraints entered in the repository. The user can use this listing to verify the information system specification or to edit the system as it exists.

Once the information system specification is complete, the conceptual schema depicted in the ORM representation of the information system is mapped to a relational database using RMAP. The RMAP process is fully described in McCormack et al (1993), which is incorporated by reference as if fully set forth herein. By way of example, for an example set of facts:

Person lives at address

Person has Phone Number

Person studies Subject

Subject is taught by Person

if the relational database associated with an example fact tree is:

Person₋₋ Table: (Person, Address)

Phone₋₋ Table: (Person, Phone Number)

Studies₋₋ Table: (Person, Subject Studied)

Subject₋₋ Table: (Subject, Teacher Person)

The associated RMAP mappings would be:

    __________________________________________________________________________     FACT          TABLE   FIRST NOUN COLUMN                                                                           SECOND NOUN COLUMN                          __________________________________________________________________________     Person lives at address                                                                      Person.sub.-- Table                                                                    Person       Address                                     Person has Phone Number                                                                      Phone.sub.-- table                                                                     Person       Phone Number                                Person studies Subject                                                                       Studies.sub.-- Table                                                                   Person       Subject Studies                             Subject is taught by Person                                                                  Subject.sub.-- Table                                                                   Person       Teacher Person                              __________________________________________________________________________

The first step in query processing is specifying the fact-tree. In Fact-Tree Specification, the user selects a noun relevant to the query. For example, if the user wanted to find out the address, phone number, subjects studied, and teachers of Mr. Smith, they would start with the Person noun because the query is basically about a person. After choosing Person as the root of the query, they can select more information about the person--to find out their address etc. The only information they are able to select is the information contained in the facts about the person, i.e.

    ______________________________________                                         0            A person lives at an address.                                     0            A person has a phone number.                                      0            A person studies a subject.                                       0            A person teaches a subject.                                       ______________________________________                                    

This set of facts is all of the information possible about a particular person. The information is displayed conceptually and the user didn't need to know any special keywords or phrases. In this case the user would select the facts

    ______________________________________                                         0            A person lives at an address.                                     0            A person has a phone number.                                      O            A person studies a subject.                                       O            A subject is taught by a person.                                  ______________________________________                                    

since that is what they want to know about Mr. Smith. This would build up the following fact-tree.

    ______________________________________                                         Person                                                                         .sub.-- that lives at an address                                               .sub.-- that has a phone number                                                .sub.-- that studies a subject                                                                .sub.-- that is taught by a person.                             ______________________________________                                    

Finally, the user would restrict the person at the root of the tree to be equal to Mr. Smith, since this is the only person they are interested in.

The meaning of the final tree is: Show the person Mr. Smith, the address that he lives at, the phone numbers that he has, the subject that he studies, and for the subjects he studies, show the people that teach those subject.

After generating the fact-tree, the user verifies that the fact-tree is correct using the Tree Interpreter of the present invention. Doing so will preclude the possibility of an ambiguous query being generated. In use, the Tree Interpreter algorithm constructs a natural language description of the fact-tree. This algorithm is a recursive depth-first search function which is described in the following best mode section. This interpretation allows the user to verify that the question he or she is asking will retrieve the information desired.

Once the user has specified the fact-tree and checked it using the Tree Interpreter, all that remains to do is generate the relational query itself. The algorithm to do this is again recursive on fact-tree nodes, and is detailed in the following section detailing the best mode of carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the present invention may be more readily understood with reference to the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings, wherein like reference characters designate like elements.

FIG. 1 is a diagram of the external view of a digital, programmable, general purpose computer configured for operation of the present invention.

FIG. 2 is a block diagram of the computer of FIG. 1 configured with the present invention.

FIG. 3 is a flow chart illustrating the initial selection menu of the present invention, after selecting the Fact Compiler of the present invention.

FIG. 4 is a flow chart illustrating the Fact Compiler of the present invention, including it's three main functions.

FIG. 5 is a flow chart illustrating the Drag and Drop over Diagram function of the Fact Compiler of the present invention.

FIG. 6 is a flow chart of the Drag and Drop Parse function invoked by the Drag and Drop over Diagram function.

FIG. 7 is a flow chart of the Compile into Repository Only function invoked by the Fact Compiler.

FIG. 8 is a flow chart of the Parse function invoked by the Compile into Repository Only function.

FIG. 9 is a flow chart of the Scan function invoked by the Parse function.

FIG. 10 is a table indicating the procedure for entering an error condition according to the present invention.

FIG. 11 is a flow chart illustrating the Look for Object Specifications function invoked by the Parse function.

FIG. 12 is a flow chart representing the Look for Fact Specifications function invoked by the Parse function.

FIG. 13 is a flow chart representing the Look for Constraint Specifications function invoked by the Parse function.

FIG. 14 is a flow chart illustrating the Allocate a New Object function invoked by the Look for Object Specifications function.

FIG. 15 is a flow chart illustrating the Allocate a New Fact function invoked by the Look for Fact Specifications function.

FIG. 16 is a flow chart illustrating the Allocate a New Constraint function invoked by the Look for Constraint Specifications function.

FIG. 17 is a flow chart representing the Update Record in Repository function invoked by both the Drag and Drop Parse and Compile into Repository Only functions.

FIG. 18 is a flow chart illustrating the initial selection menu of the present invention, after selecting Fact Tree Specification according to the present invention.

FIG. 19 is a flow chart illustrating the Fact Tree Formation function and selection of either the Query Mapper or Tree Interpreter functions of the present invention.

FIG. 20 is a flow chart representing the Fact Tree to SQL Query function invoked when a user selects the Query Mapper function of the present invention.

FIG. 21 is a flow chart illustrating the Node to SQL function invoked by the Fact Tree to SQL function.

FIG. 22 is a flow chart representing the Create Join function invoked by the Node to SQL function.

FIG. 23 is a flow chart illustrating the Add Selector 1 function invoked by the Node to SQL function.

FIG. 24 is a flow chart illustrating the Add Selector 2 function invoked by the Node to SQL function.

FIG. 25 is a flow chart of the Fact Tree to Description function invoked when a user selects the Tree Interpreter of the present invention.

FIG. 26 is a flow chart of the Create Text for Root function invoked by the Fact Tree to Description function.

FIG. 27 is a flow chart illustrating the Create Text for Node function invoked by the Fact Tree to Description function.

BEST MODE OF CARRYING OUT THE INVENTION

The preferred embodiment of the present invention incorporates computer system 1 configured as shown in FIG. 1. Computer system 1 is a programmable digital computer. The invention is executable on an IBM compatible computer having an Intel 80386 or higher chip set, operating under the MS-DOS operating system, version 5.0 or higher. A minimum or 6 megabytes of available RAM is required for execution, as is a minimum of 6 megabytes of available hard disk storage space. These computers typically include a CPU, main storage, I/O resources, and a user interface, including a manually operated keyboard and mouse. The present invention also requires a graphical user interface program: Microsoft Windows is one well known example.

The present invention was programmed on an IBM compatible computer having an Intel 80486 chip set, running Microsoft MS-DOS operating system, version 5.0. Microsoft Windows Version 3.1 was installed to provide the required graphical user interface. Finally, the system whose description follows was programmed in the Borland C language.

FIG. 2 depicts the bus structure of the general purpose programmable computer of FIG. 1, with the present invention implemented thereon.

Referring now to FIG. 3, a user initiates the system at manual input 50 and selects the desired function at function selection 51. The fact compiler of the present invention is selected at 100. The fact tree of the present invention is selected at 300. The present invention provides a method and apparatus that allows users to:

1. Develop an information system description using a graphical user interface to a natural language-like computer language. One such language is FORML.

2. Specify the fact tree for query generation.

3. Check queries for semantic correctness.

4. Generate queries to the database system.

Once it has been determined that an information system needs to be created, the Fact Compiler of the present invention is invoked. The Compile function of the Fact Compiler enables a user to type in text, using a natural language-like computer language. One such language is FORML. The text is typed in a window provided by the system, and may contain objects, facts and/or constraints. Using a translation function called "Drag and Drop over Diagram" and a graphical user interface, the user then drags the text from the entry window to the appropriate place over the ORM conceptual schema diagram of the Fact Compiler. The user then drops the text onto the diagram. The Fact Compiler validates the text entered and notifies the user of any errors encountered. During validation, the Fact Compiler first parses the text and creates an object list, a fact list and a constraint list in memory. Then the Fact Compiler iteratively compiles the text into the repository. The repository is essentially a "database of databases". Finally, the validated objects, facts and/or constraints are drawn in proper notation on the ORM conceptual schema diagram. At this point the information system specification may be considered complete.

After the information system has been created, the user may wish to check and/or edit the previously entered information. This is accomplished by using the Decompile function of the Fact Compiler. Decompile is essentially the reverse of the previously discussed Compile function, in that it takes an ORM conceptual schema diagram and returns a textual listing of the objects, facts and constraints entered in the repository. The user can use this listing to verify the information system specification or to edit the system as it exists.

Once the information system Specification is complete, the conceptual schema depicted in the ORM representation of the information system is mapped to a relational database using RMAP. The RMAP process is fully described in McCormack et al (1993), which is incorporated by reference as if fully set forth herein. By way of example, for an example set of facts:

Person lives at address

Person has Phone Number

Person studies Subject

Subject is taught by Person

if the relational database associated with an example fact tree is:

Person₋₋ Table: (Person, Address)

Phone₋₋ Table: (Person, Phone Number)

Studies₋₋ Table: (Person, Subject Studied)

Subject₋₋ Table: (Subject, Teacher Person)

The associated RMAP mappings would be:

    __________________________________________________________________________     FACT          TABLE   FIRST NOUN COLUMN                                                                           SECOND NOUN COLUMN                          __________________________________________________________________________     Person lives at address                                                                      Person.sub.-- Table                                                                    Person       Address                                     Person has Phone Number                                                                      Phone.sub.-- table                                                                     Person       Phone Number                                Person studies Subject                                                                       Studies.sub.-- Table                                                                   Person       Subject Studies                             Subject is taught by Person                                                                  Subject.sub.-- Table                                                                   Person       Teacher Person, if the relational           database associated with an example fact tree is:                              __________________________________________________________________________

The first step in query processing is specifying the fact-tree. In Fact-Tree Specification, the user selects a noun relevant to the query. For example, if the user wanted to find out the address, phone number, subjects studied, and teachers of Mr. Smith, they would start with the Person noun because the query is basically about a person. After choosing Person as the root of the query, they can select more information about the person--to find out their address etc. The only information they are able to select is the information contained in the facts about the person, i.e.

    ______________________________________                                         0            A person lives at an address.                                     0            A person has a phone number.                                      0            A person studies a subject.                                       0            A person teaches a subject.                                       ______________________________________                                    

This set of facts is all of the information possible about a particular person. The information is displayed conceptually and the user didn't need to know any special keywords or phrases. In this case the user would select the facts

    ______________________________________                                         0            A person lives at an address.                                     0            A person has a phone number.                                      O            A person studies a subject.                                       O            A subject is taught by a person.                                  ______________________________________                                    

since that is what they want to know about Mr. Smith. This would build up the following fact-tree.

    ______________________________________                                         Person                                                                         .sub.-- that lives at an address                                               .sub.-- that has a phone number                                                .sub.-- that studies a subject                                                                .sub.-- that is taught by a person.                             ______________________________________                                    

Finally, the user would restrict the person at the root of the tree to be equal to Mr. Smith, since this is the only person they are interested in.

The meaning of the final tree is: Show the person Mr. Smith, the address that he lives at, the phone numbers that he has, the subject that he studies, and for the subjects he studies, show the people that teach those subject.

After generating the fact-tree, the user verifies that the fact-tree is correct using the Tree Interpreter of the present invention. Doing so will preclude the possibility of an ambiguous query being generated. In use, the Tree Interpreter algorithm constructs a natural language description of the fact-tree. This algorithm is a recursive depth-first search function which can be summarized as follows:

    __________________________________________________________________________     function: Interpret.sub.-- Tree (fact-tree.sub.-- node) Il                     Interpret.sub.-- Tree operates on a node of                                    the fact.sub.-- tree                                                           begin                                                                          If the node is the root of the tree then                                       noun is the noun in the node                                                                       e.g. Person                                                Print `For all noun(s)`                                                                            e.g. For all Person(s)                                     if the node has a restriction then                                                                 e.g. is equal to Mr. Smith                                 print "(where noun restriction)"                                                                   e.g.(where Person = Mr.Smith)                              Print "show:" and move on to a new line                                        otherwise                                                                      noun is the noun in the node                                                                              e.g. Address                                        parent-noun is the noun in the node's parent                                                              e.g. Person                                         phrase is the phrase in the noun                                                                          e.g. lives at                                       Print "the noun(s) that the parent-noun phrase"                                                           eg. the Address(es)                                                            that the person                                                                lives at                                            if the node has a restriction then                                                                        e.g. is equal to                                                               Seattle                                              print "(where noun restriction)"                                                                         eg. (where address =                                                           Seattle)                                            if the node has any children then                                               print ", and for those noun(s) show:"                                          move on to a new line                                                         for all children of the node do                                                call Interpret.sub.-- Tree on the child-node                                   end                                                                            __________________________________________________________________________

The result of Interpret₋₋ Tree on the example fact-tree would be

    ______________________________________                                         For all Person(s) (where Person = Mr. Smith) show:                             the Address that the Person lives at                                           he Phone Number that the Person has                                            the Subjects that the Person studies,                                          and for those subjects show the Person(s) that the Subject is                  taught by.                                                                     ______________________________________                                    

This interpretation allows the user to verify that the question he or she is asking will retrieve the information desired.

Once the user has specified the fact-tree and checked it using the tree interpreter, all that remains to do is generate the relational query itself. The algorithm to do this is again recursive on fact-tree nodes.

    ______________________________________                                         function Create.sub.-- Query (fact-tree.sub.-- node)                           begin                                                                          node is the node being mapped by this call to the function                     child i . . . childn are the children of node                                  sentence1, . . . sentencen. are the respective sentences child i . . .         childn each sentence i, (i=1 . . . n) has a mapping' associated                with it. The mapping corresponds to the relational structure used              to represent the sentence and contains the table that the sentence             was mapped to, the column for the first noun and the column                    for the second noun. For example, the sentence Person lives                    at Address maps to the Person table, with noun1 (person) being                 column 1, and noun2 (address) being column 2.                                  Join all of the mappings for sentences 1. . . n together using outer           joins based on the noun in node and the respective positions of                that noun in sentences 1 to n. Form a query, including                         restriction when required.                                                     ______________________________________                                    

An SQL query representative of this applied to the example fact-tree would be:

    ______________________________________                                         select Person. Person, Phone Number, Subject                                   from Person, Person has Phone.sub.-- Number, Person.sub.-- studies.sub.--      Subject                                                                        Outer join Person.Person = Person has Phone.sub.-- Number.Person               Outer join Person.Person = Person.sub.-- studies.sub.-- Subject.Person         wherePerson.Person = `Mr. Smith`. . .                                          ______________________________________                                    

If any childi i=1. . . n have children, apply Create₋₋ Query to child and use an outer join to include the result into the existing query. In the example fact-tree, this would result in Create₋₋ Query being executed on the Subject node of the Person that studies Subject branch and would result in the query:

    ______________________________________                                         select Person.Person, Phone Number, Person.sub.-- studies.sub.-- Subject.      Subject Subject.Person                                                         from Person, Person.sub.-- has.sub.-- Phone Number,                            Person.sub.-- studies.sub.-- Subject, Subject                                  Outer join Person.Person=Person.sub.-- has.sub.-- Phone.sub.-- Number.Pers     on                                                                             Outer join Person.Person = Person.sub.-- studies.sub.-- Subject.Person         Outer join Person.sub.-- studies.sub.-- Subject.Subject                        = Subject.Subject                                                              where Person.Person = `Mr. Smith . . .                                         ______________________________________                                    

Note that SQL is used as a notational convenience and its use has no bearing on the theory behind the algorithm. It is a particular feature of the present invention that any relational language could have been used. The advantages of the Fact Compiler, Query Mapper and Tree Interpreter algorithms of the present invention are that they substantially reduce the number of concepts and amount of training required for a naive end-user to express meaningful queries in a relational database. The algorithm set of the present invention allows users to form conceptual queries without having to know keywords and physical structures. Also, the algorithms of the present invention provide a generated natural language description of the query to assure that the query is correct in syntax. These advantages are illustrated by contrasting the previously described example with the same example expressed in the state of the art natural language and SQL implementations.

To express the query in natural language, the user would need to construct and type in the query:

Show me the person called Mr. Smith, his Address, his Phone Number, the subjects he studies, and for those subjects show people who teach them The distinct pieces of information required to phrase this query are:

1. An overall knowledge of how to express the query (having to include keywords like person, etc.)

2. The knowledge that you could ask for Address, Phone Numbers, Subjects, etc . . .

Fact Compiler

The fact complier of the present invention is selected at 100. The fact tree of the present invention is selected at 300. As explained above a Fact Compiler is provided by the present invention, a detailed description of which follows. Referring now to FIG. 4, after selecting fact compiler 100, the user opens a diagram which represents one level of the information system to be modelled. After opening the fact compiler diagram, the user types in a factual sentence, an object type, or a constraint, using a natural language-like computer language. One such language is FORML. An example of such an input is "the INSTRUCTOR with the ID "100" is qualified to teach the SUBJECT with the name "database design" at the SUBJECT LEVEL 300". At this point, the user may select one of three options: validate the input using Validate Only function 105; compile the information only into the repository 140; or to drag and drop the fact over the diagram at function 120.

Referring now to Validate Only function 105 of FIG. 4 of the present invention, after all text has been combined from the edit windows at 110, it is parsed into its component words using function 111. An error checker at 112 determines if there are errors in the text which is input. If there are no errors, the system indicates successful validation at 113. If error checker 112 determines that there are errors in the textual input, the errors will be shown at error window 114.

Drag and Drop over Diagram function 120, is detailed in FIG. 5. After the user selects Drag and Drop over Diagram at 120, the user utilizing a mouse moves a pointer over the icon from the edit window at 121. The user presses the left mouse button down and holds it down at 122. The system will test for the type of item which was input in the edit window at 123. Item kind selector 124 will change the nature of the cursor depending upon the type of information input in the edit window. If the data input is a fact, the cursor will change to a fact cursor at 125. If the data input is a constraint, the cursor will be changed to a constraint cursor at 126. If the data input is an object, the cursor will change to an object cursor at 127. The user drags the modified cursor over the diagram at 128. The edit window will disappear while the cursor is being moved. If the cursor moves over a non-drawing area the cursor change to a "Can't Draw" cursor. In the event the user needs to reorient the direction of the data which is input, the right mouse button is used. For each click of the right mouse button, the icon changes its orientation 90° at 130. When the user releases the left mouse button at 131, the cursor will drop the data over the diagram. Cursor checker 132 determines if the cursor is actually over the diagram or not. If it is, Drag and Drop Parse function 135 is invoked. If not, an indication is given the user that the cursor is not in the diagram.

Drag and Drop Parse function 135 is detailed in FIG. 6. After collecting text at the current edit window, the text is parsed using Parse function 142. After parsing an error checker 161 determines if an error has been made in the textual input. If no error has been made, the record is updated to the repository using the Update Record to Repository function 149. After the record has been updated to the repository, the item is drawn on the diagram using Draw Item on Diagram function 164. At error checker 161, should an error condition be determined to exist, Enter Error Condition function 162 is invoked and function 135 exited at 165.

Referring again to FIG. 4, function 140 gives the user the option of compiling the input into the repository only. Function 140 is detailed in FIG. 7. After selecting function 140, Compiling into Repository Only, the system combines all text from the edit windows at 141 and parses the input data using Parse function 142. Error checker 143 determines if an error has been made in the textual input. If errors have been made, they are shown at error window 145. In the event no errors were incurred, successful compilation is shown in the status bar at 144. An iterative process is detailed at 146. Each of the lists generated, the object list, fact list and constraint list, is searched record by record. Each record is retrieved from it's respective list at 147 and its status tested at 148. In the event the record has been changed, function 149, which updates the record to the repository, is invoked. In the event the record has not been changed, the list pointer is incremented at 150 and a new record is retrieved from the list. In the event the record is new, function 149 is again invoked after which the record type is tested at 152. If the new record is an object, function 152, which allocates a new object, is invoked. In the event the new record is a fact, a new fact is allocated using function 154. If the new record type is a constraint, a new constraint is allocated at 155. Following any of these allocations, the list pointer is again incremented at 150.

Parse function 142 of FIGS. 6 and 7 is detailed at FIG. 8. After Parse function 142 is invoked, it invokes Scan function 170 to retrieve a token. After the token is retrieved, it is partitioned into sections at 171. An iterative loop through each of the tokens is set up at 172. Each token is tested for its type at 173. In the event the section is an object, function 174, which looks for object specifications, is invoked. In the event the section is a fact, function 175, which looks for fact specifications is invoked. In the event the section being tested is a constraint, function 176 is invoked which looks for constraint specifications. After either functions 174, 175 or 176 have been invoked, a test is made to determine if the section tested is the terminal section. If not, the next section is subjected to the same test. In the event the section is a terminal section, Parse function 142 is exited at 179.

Scan function 170 of FIG. 8 is detailed at FIG. 9. After Parse function 142 invokes Scan function 170, it reads characters from the input source text at 180. At 181, the function matches each character sequence with a token specification shown as regular expressions in the Lexical Analyzer Declarations at 181, after which the token is returned at 182.

Function 162, Enter Error Condition which was previously invoked at FIG. 6, is detailed at FIG. 10. For each error encountered, the system will retrieve the character position and line number where the error occurred. This function will then store the error number, error text and error context information in an error list.

Referring again to FIG. 8, function 174, Look for object Specification, is detailed at FIG. 11. When function 174 is invoked, the object is syntactically specified by any "Object Declaration" at 190. The function continues to "parse" and "scan". A determination is made at 191 as to whether it is still an object section. If not, the function exits at 192. If the object is still in the object section, it breaks the textual components into structures for storing in the object list at 193. At 194, the object status is tested. If it is a new object, function 220 which allocates a new object, is invoked, If the object already exists in an object list, function 174 is exited at 198. If the object exists in the repository but it is not in the object list, the system reads the structure at 196 from the repository and puts it in the object list. After either function 196 or 220 is invoked, the function is again exited at 198.

Function 175, Look for Fact Specification, previously invoked at FIG. 8, is detailed in FIG. 12. After function 175 is invoked, the fact is syntactically specified by a "fact declaration". The system continues to "parse" and "scan". A determination is made at 201 as to whether the fact is still in the fact section. If not, function 175 is exited at 202. If it is still in the fact section, the system breaks the textual components into structures for storing in a fact list at 203 after which the fact status is tested at 204. If the fact is a new fact, function 230 is invoked, which allocates a new fact after which fact parsing is exited at 206. If the fact already exists in a fact list, the function 175 again exits at 206. If the fact exists in the repository but is not in the fact list, the system reads the structure at 205 from the repository and puts it in the fact list, after which function 175 exits once again at 206.

Function 176, also previously invoked at FIG. 8, is detailed at FIG. 13. When function 176 is invoked to look for constraint specifications, a constraint is syntactically specified by a "constraint declaration" at 210. The system continues to "parse" and "scan". At 211 a determination is made if the constraint is still in the constraint section. If not, function 176 is exited at 212. If the constraint is still in the constraint section, the system breaks the textural components into structures for storing in the constraint list at 213. After which the constraint status is tested at 214. If a new constraint, function 240 is invoked, which allocates a new constraint. If the constraint already exists in the constraint list, function 176 is exited at 217. If the constraint exists in the repository but it is not in the constraint list, the function reads the structure from the repository and puts it in the constraint list at 216. After either function 240 or process 216 is accomplished, function 176 exits at 217.

Function 220, previously invoked in FIG. 11, is detailed in FIG. 14. Function 220 creates an empty object structure at 221, enters the name and all object attributes into the structure at 222, places the object structure in the object list at 223, and exits at 224.

Function 230, previously invoked in FIG. 12, is detailed in FIG. 15. Function 230 creates an empty fact structure at 231. At 232 the function puts the predicate text, the objects involved and internal constraint information into the structure. At 233, the function places the fact structure into the fact list and exits at 234.

Function 240, previously invoked at FIG. 13, is detailed in FIG. 16. Function 240 allocates a new constraint as follows: it creates an empty constraint structure at 241. At 242 it puts the constraint information (role positions, predicate IDs) into the structure. At 243 the function places the constraint structure into the constraint list and exits at 244.

Function 149, previously invoked in both FIGS. 7 and 8, is detailed in FIG. 17. After function 149 is invoked, an updated record exists in a fact list, an object list or a constraint list, as shown at 250. At 251, the record type is tested. If the record is an object, the object structure is sent the object update function at 252. If the record is a fact, the fact structure is sent to the fact update function at 254 and if a constraint structure is sent to a constraint update function at 253. After any of the aforementioned update functions is accomplished, function 149 is exited at 256.

Fact Tree Formation

Referring to FIG. 18, the second option possible from function selection is initiation of Fact Tree Specification 300, which is detailed at FIG. 19. Referring to FIG. 19, the fact-tree is formed at 300. An example of a fact tree is:

    ______________________________________                                         Person (= Mr Smith)  restriction                                               that person lives at an address                                                that has a phone number   noun                                                 that studies a subject                                                                       that is taught by a Person                                                               phrase                                                 ______________________________________                                    

Each node in the fact tree has a noun (e.g. Person).

Each node in the fact tree may have a restriction (e.g.=Mr Smith).

Each non-root node in the fact tree (all but the very top node) has a phrase (e.g. is taught by).

The root of the tree is then assigned to the variable Root at 301. In this case, the shaded node (Person) is assigned to Root.

If the fact tree is to be mapped to an SQL query, Root is passed as the parameter to the function Fact₋₋ Tree₋₋ To₋₋ SQL 400. The return value of this function will be an SQL query. Fact₋₋ Tree₋₋ To₋₋ SQL is described using functions 400 to 465.

If the fact tree is to be mapped to an English description, Root is passed as the parameter to the function Fact₋₋ Tree₋₋ To₋₋ Description (500). This function has no return value. The result of Fact Tree To Description will be to print out the description of the tree. Fact₋₋ Tree₋₋ To₋₋ Description is described using functions 500 to 535.

Tree Interpreter

The present invention also provides a Tree Interpreter, invoked as "Fact₋₋ Tree₋₋ to₋₋ Description", a detailed description of which follows. Referring to FIG. 25, Fact₋₋ Tree₋₋ To₋₋ Description (500) is a recursive function that takes a node of a fact tree as input and returns a description of the query represented by that tree or sub-tree. The parameter Root is the node on which the function is to operate.

Function 501 assigns some working variables. Root is the root of a tree of subtree that may or may not contain a parent and may or may not contain children. For example, if the shaded node in the example tree (Parent) was passed to Fact₋₋ Tree₋₋ To₋₋ Description, there would be no parent, and three children. Parent is assigned Root's parent (in this case NULL). Nodes is assigned the number of Root's children (three). Child[i . . . Nodes] is an array which is assigned Root's children (the three children of Person--"that lives at Address", "that has a phone number", and "that studies a subject".

Next, the temporary variable Text is assigned the "description" of the Root. (502-504). If Root has no parent (it is the root of the fact tree), the Root is passed to the function 503 Create₋₋ Text₋₋ For₋₋ Root (503), otherwise Root is passed to Function 507, Create₋₋ Text₋₋ For₋₋ Node. The return value of both of these functions is the description of Root.

At 505, Text is then printed out followed by a carriage return. If Root referred to the Person node, Function 503, Create Text For Root would have been used and Text would be "For all Person(s) (where Person=Mr Smith) show:" If Root referred to the "that studies Subject" node, function 504, Create Text For Node would have been used and Text would be "the Subject(s) that the Person studies, and for those Subject(s) show: ".

The next step is to recursively process Root's children using a depth-first-search algorithm, detailed in functions 505-510. Nodes is the number of Root's children and Child[i . . . Nodes] are Root's actual children.

The variable I is used as a counter variable. It is initially assigned to 1 at 506. If I is greater than Nodes (there are no more children to process), this instantiation of Fact₋₋ Tree₋₋ To₋₋ Description is complete (507-508) otherwise, Fact₋₋ Tree₋₋ To₋₋ Description is invoked for Child[i] at 509, I is incremented at 510 and the loop continues (507) until there are no more children to process.

The result of Fact₋₋ Tree₋₋ To₋₋ Description applied to the Person node in the example tree would be:

    __________________________________________________________________________                          the Address that the Person lives at                      Output                                                                         For all Person(s) (where Mr. Smith) show:                                                           the Phone Number that the Person has                      the Subjects that the Person studies,                                          and for those subjects show:                                                                          Processing                                              The Person(s) that the Subject                                                                      Fact.sub.-- Tree To .Description called on Person         is taught by                                                                                          Fact.sub.-- Tree To .Description called on                                     that lives at Address                                                          Fact Tree To .Description called on                                            that has phone number                                                          Fact.sub.-- Tree To .Description called on                                     that studies subject                                                             Fact Tree To Description called on                                             that Is taught by Person                              __________________________________________________________________________

Function 503, is invoked in FIG. 25 and Create₋₋ Text₋₋ For₋₋ Root, takes the root node of a fact tree as an argument (Root) and returns the description of that node.

At 520, Root contains a noun (e.g. Person); this is assigned to Noun. Root may also contain a Restriction (e.g.=Mr Smith); this is assigned to Restriction. The variable Text is assigned `For all`+noun+`(s)` (e.g. `For all Person(s)`).

If Root contains a Restriction, that restriction is added to Text at 521 and 522. (e.g. Text="For all Person(s)(where Person=Mr Smith)") "show": `is added to Text at 523 and

Text is returned at 524 (e.g. Text="For all Person(s)(where Person=Mr Smith) show:").

Referring back to FIG. 25, Create₋₋ Text₋₋ For₋₋ Node (504), which takes a non-root node of a fact tree as an argument (Root) and returns the description of that node is detailed at FIG. 27. For example, the node `that studies a Subject` could be passed as an argument.

At 530 Root contains a noun (e.g. Subject), this is assigned to Noun. Root contains a phrase (e.g. `studies`) this is assigned to Phrase. Root's parent contains a noun (e.g. Person), this is assigned to Parent-Noun. Root may also contain a Restriction (e.g.=Mr Smith) this is assigned to Restriction. The variable Text is assigned `the`+noun+`(s) that the`+Parent-Noun+``+Phrase (e.g. `the Subject(s)-that the Person studies`).

If Root contains a Restriction, that restriction is added to Text at 531 and 532. If Root has children', and for those'+Noun+`:(s) show:` is added to Text at 533 and 534.

At 535, Text is returned (e.g. Text=`the Subject(s) that the Person studies, and for those Subject(s) show:`).

Query Mapper

The present invention also provides a Query Mapper, invoked as "Fact₋₋ Tree₋₋ to SQL₋₋ Query", a detailed description of which follows. Referring back to FIG. 19, function 400 is detailed at FIG. 20. This function takes the root node of a fact tree as input and returns an equivalent SQL query. The parameter Root is the root of the tree on which the function is to operate.

Each non-root node in the fact tree (all but the very top node) has a relational mapping associated with it. The relational mapping specifies the node's representation in a relational database. By way of example, for an example set of facts:

Person lives at address

Person has Phone Number

Person studies Subject

Subject is taught by Person

if the relational database associated with an example fact tree is:

Person₋₋ Table: (Person, Address)

Phone₋₋ Table: (Person, Phone Number)

Studies₋₋ Table: (Person, Subject Studied)

Subject₋₋ Table: (Subject, Teacher Person)

The associated RMAP mappings would be:

    __________________________________________________________________________     FACT          TABLE   FIRST NOUN COLUMN                                                                           SECOND NOUN COLUMN                          __________________________________________________________________________     Person lives at address                                                                      Person.sub.-- Table                                                                    Person       Address                                     Person has Phone Number                                                                      Phone.sub.-- table                                                                     Person       Phone Number                                Person studies Subject                                                                       Studies.sub.-- Table                                                                   Person       Subject Studies                             Subject is taught by Person                                                                  Subject.sub.-- Table                                                                   Person       Teacher Person                              __________________________________________________________________________

Table denotes the table in which the fact is stored. First Noun Column denotes the column for the node's parent. Second Noun Column denotes the column for the node's noun.

For example, the mapping associated with (Person) lives at Address means that all addresses are stored in the Person Table table, with the people who live at them in the Person column and the actual addresses in the Address column.

The predicate mappings are derived by an algorithm similar to the one described in McCormack & Halpin, Automated Mapping of Conceptual Schemas to Relational Schemas, Proc CAiSE 93, Sorbonne University, Paris, 1993.

An SQL query contains three parts, a SelectList, a From List, and a WhereClause. These are gradually build up using recursive calls to Node₋₋ To₋₋ SQL.

Initially, SelectList, Frogist, and WhereClause are set to the empty string ("") at 401.

At 402, Node₋₋ To₋₋ SQL is called, with Root as its parameter, to build up the query.

At 403,404 and 405, SelectList, Fromlist, and WhereClause are respectively formatted. At 406, the query is assembled as the result of the function and returned at 407.

Node₋₋ To₋₋ SQL is invoked at 402. This is a recursive function that maps a node of a fact tree into an SQL query. Successive calls to this function build up the SelectList, Frogist, and WhereClause variables.

Node₋₋ To₋₋ SQL has three parameters. The first, Root, is the root of the tree or sub tree being mapped. The second and third parameters are the table and column used to join the query for Root's sub tree to the rest of the query.

At 410, Parent is the parent of Root, Nodes is the number of children of Root and Child[i . . . Nodes] are the children of Root.

If Root has no children, no processing is required so the function simply returns (411, 412).

Otherwise, the children of Root are added to the query as follows:

If Root has a parent, it needs to be joined into the query using the JoinTable and JoinColumn function 413 and 414; and Root needs to be added to the select list of the query at 415.

To join all of Root's children into the query, they are processed sequentially as follows: The counter variable i is initialized to 1 at 416. The value of nodes is checked at 417, and if i is less than nodes Add₋₋ Selector₋₋ 2 (node) is invoked at 419. Each child is added to the select-list using Add₋₋ Selector₋₋ 2 at 419, and that child's children are added into the query using recursive calls to function 421, Node₋₋ To₋₋ SQL. The selector for each node is used to join the subtree's queries together at 420. Create₋₋ Join, invoked at 414 is detailed at FIG. 22. This function joins a subquery to the main query by adding an inner join to the where-clause. The join is based in the first noun in the passes node (Node) and the passed parameters.

Referring back to FIG. 21, function 415, Add₋₋ Selector₋₋ 1 is detailed at FIG. 23. This function adds Node's table to the FromList and the column for Node's first noun to the SelectList.

Referring again to FIG. 21, function 419, Add₋₋ Selector₋₋ 2 is detailed at FIG. 24. This function adds Node's table to the FromList and the column for Node's second noun to the SelectList.

It is to be understood that the above-described embodiments are merely illustrative of some of the many specific embodiments which represent applications of the principles of the present invention. Clearly, numerous variations can be readily devised by those skilled in the art without departing from the scope of the present invention. 

What is claimed is:
 1. Apparatus for generating a query to an information system, said information system having been created using a drag-and-drop information system specification means utilizing a computer language having both textual and graphical forms for translating natural language-like constructs into object-role modeling symbology, said information system specification means further for entering text, utilizing the textual form of said computer language, onto a display device, for parsing said text into at least one of object, fact and constraint into a repository, for forming a conceptual schema representing said information system, and for mapping said conceptual schema to a database, said apparatus implemented on a programmable computer including memory, data entry means, said display means, a graphical user interface, and having said repository implemented thereon, said apparatus using said natural language-like constructs for specifying said query to said information system by providing means for displaying said conceptual schema utilizing said graphical form of said computer language, drag and drop cursor control means for moving a cursor over said conceptual schema diagram and for selecting a first object, and fact tree formation means for forming a fact tree from a first object stored in said repository and displayed on said conceptual schema diagram, said first object forming the root node of a fact tree, said apparatus further comprising:relational query mapping means for mapping said query to said database and for returning said query in a language appropriate to said database, said query mapping means utilizing said root node defined by said first object, which first object is displayed using utilizing said graphical form of said computer language, and selected by said drag and drop cursor control means.
 2. The apparatus of claim 1 wherein:said fact tree formation means is further for forming said fact tree from a fact stored in said repository, said fact further selected from said conceptual schema diagram, said first object forming said root node of a fact tree, said fact forming a non-root node of said fact tree; and said relational query mapping means is further for returning said query using said fact as a non-root node.
 3. The apparatus of claim 1 wherein:said fact tree formation means is further for forming said fact tree from a constraint stored in said repository, said constraint further selected from said conceptual schema diagram, said first object forming said root node of a fact tree, said constraint for restricting said root of said tree to a given instance of said first object; and said relational query mapping means further for returning said query restricted to said given instance of said first object defined by said constraint.
 4. The apparatus of claim 1 wherein said query mapping means further comprises:query variable initialization means, responsive to a call to said query mapping means, for initializing query variables, said query variables comprising Root, WhereClause, FromList and SelectList, JoinTable and JoinColumn; said Root variable initialized to the value of root, and said WhereClause, FromList and SelectList, JoinTable and JoinColumn variables being initialized to a null value; query build means, responsive to said query initialization means, for receiving said Root, JoinTable and JoinColunm variables, and building said query; query variable format means format means for formatting said query variables after said query variables are returned from said query build means; query assembly means for assembling said query from said query variables; and query return means for returning said query mapping means.
 5. The apparatus of claim 4 wherein said query build means further comprises:local build variable initialization means, responsive to invocation of said query build means for initializing local build variables, said local build variables comprising Root, Parent, Nodes and Child(i . . . nodes), Table and Column where said Root variable is set to the value of root, said Parent variable is set to the value of the parent of said root, said Nodes variable is the number of children of said root, Child(i . . . n) are children of said root, said Table variable is the table from said Child(i . . . n)'s mapping and said Column is the column for a second noun from said Child(i . . . n)'s mapping; nodes checking means, responsive to said value of said Nodes variable, for returning to said query mapping means if said nodes checking means determines the value of said Nodes variable to be equal to zero; parent checking means, responsive to a determination by said nodes checking means that the value of said nodes variable is greater than zero, for checking if the value of said Parent variable is a null value; first selector adding means, responsive to a determination by said parent checking means that said value of said Parent variable is a null value, for updating said SelectList variable by adding to said SelectList variable the variables Table and Column, said Table variable equal to a table from said node's mapping and said Column variable equal to a column from said node's mapping, where said value of said node is equal to Child(i); join creation means, responsive to a determination by said parent checking means that said value of said Parent variable is other than a null value, for joining a subquery to said query by adding an inner-join to said WhereClause; iteration counter means for counting iterations; iteration counter initialization means for initializing said iteration counter means to a value of 1; iterative node test means for testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means, and returning to said query mapping means if said iterative node testing means determines the value of said Nodes variable to be greater than the value of said iteration counter; second selector adding means, responsive to a determination by said iterative node test means that said Nodes variable is less than or equal to the value of said iteration counter means, for adding node's Table to said FromList variable and adding said node's table and column to said SelectList variable, where said value of said node is equal to Child(i), and Child(i) is the value of said iteration counter means; recursive query build invoking means for joining queries created for child nodes of said node to said query; iteration counter incrementing means for incrementing said iteration counter means by a value of 1; and loop means for returning to said iterative node test means.
 6. A method for generating a query to an information system, said information system having been created using drag-and-drop information system specification means utilizing a computer language having both textual and graphical forms for translating natural language-like constructs into object-role modeling symbology, said information specification means further for entering text onto a display device utilizing said textual form of said computer language, for parsing said text into at least one of object, fact and constraint into a repository, for forming a conceptual schema diagram representing said information system, and for mapping said conceptual schema to a database, said apparatus implemented on a programmable computer including memory, data entry means, said display means, a graphical user interface, and having said repository implemented thereon, said method using said natural language-like constructs for specifying said query to said information system by providing means for displaying said conceptual schema utilizing said graphical form of said computer language, drag and drop cursor control means for moving a cursor over said conceptual schema diagram and for selecting a first object, and fact tree formation means for forming a fact tree from a first object stored in said repository and displayed on said conceptual schema diagram, said first object forming the root node of a fact tree, said method further comprising the steps of:mapping said query to said database with a relational query mapping means utilizing said root node defined by said first object, which first object is displayed utilizing said graphical form of said computer language, and selected by said drag and drop cursor control means; and returning said query in a language appropriate to said database.
 7. The method of claim 6 further comprising the steps of:selecting a fact from said conceptual schema diagram using said drag and drop cursor control means; forming said fact tree from said first object and said fact, said first object forming said root node of a fact tree, said fact forming a non-root node of said fact tree; and returning said query using said fact as a non-root node.
 8. The method of claim 6 further comprising the steps of:selecting a constraint from said conceptual schema diagram using said drag and drop cursor control means; forming said fact tree from said first object and said constraint, said first fact forming said root node of a fact tree, said constraint for restricting said root node of said fact tree to a given instance of said first object; and returning said query restricted to said given instance of said first object defined by said constraint.
 9. The method of claim 6 wherein said step of mapping said query to said database further comprises the steps of;initializing query variables, said query variables comprising Root, WhereClause, FromList and SelectList, JoinTable and JoinColumn; said Root variable initialized to the value of root, and said WhereClause, FromList and SelectList, JoinTable and JoinColumn variables being initialized to a null value using query variable initialization means, responsive to a call to said query mapping means; build said query using query build means responsive to said Root, JoinTable and JoinColumn variables, and to said query initialization means; formatting said query variables using query variable format means after said query variables are returned from said query build means; assembling said query from said query variables using query assembly means; and returning said query mapping means using query return means.
 10. The method of claim 24 wherein said step of building said query further comprises the steps of:initializing local build variables using local build variable initialization means responsive to invocation of said query build means, said local build variables comprising Root, Parent, Nodes and Child(i . . . nodes), Table and Column where said Root variable is set to the value of root, said Parent variable is set to the value of the parent of said root, said Nodes variable is the amber of children of said root, Child(i . . . n) are children of said root, said Table variable is the table from said Child(i . . . n)'s mapping and said Column is the column for a second noun from said Child(i . . . n)'s mapping; returning to said query mapping means if said nodes checking means determines the value of said Nodes variable to be equal to zero, using nodes checking means, responsive to said value of said Nodes variable; checking if the value of said Parent variable is a null value using parent checking means, responsive to a determination by said nodes checking means that the value of said nodes variable is greater than zero; updating said SelectList variable by adding to said SelectList variable the variables Table and Column, said Table variable equal to a table from said node's mapping and said Column variable equal to a column from said node's mapping, where said value of said node is equal to Child(i) using first selector adding means, responsive to a determination by said parent checking means that said value of said Parent variable is a null value; joining a subquery to said query by adding an inner-join to said WhereClause using join creation means, responsive to a determination by said parent checking means that said value of said Parent variable is other than a null value; counting iterations using iteration counter means; initializing said iteration counter means to a value of 1 using iteration counter initialization means; testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means, and returning to said query mapping means if said iterative node testing means determines the value of said Nodes variable to be greater than the value of said iteration counter means using iterative node test means; adding node's table to said FromList variable and adding said node's table and column to said SelectList variable, where said value of said node is equal to Child(i), and Child(i) is the value of said iteration counter means using second selector adding means, responsive to a determination by said iterative node test means that said Nodes variable is less than or equal to the value of said iteration counter means; joining queries created for child nodes of said node to said query using recursive query build invoking means; incrementing said iteration counter means by a value of 1 using iteration counter incrementing means; and returning to said iterative node test means using loop means.
 11. Apparatus for generating a query to an information system, said information system having been created using a drag-and-drop information system specification means utilizing a computer language having both textual and graphical forms for translating natural language-like constructs into object-role modeling symbology, said information system specification means further for entering text, utilizing the textual form of said computer language, onto a display device, for parsing said text into at least one of object, fact and constraint into a repository, for forming a conceptual schema representing said information system, and for mapping said conceptual schema to a database, said apparatus implemented on a programmable computer including memory, data entry means, said display means, a graphical user interface, and having said repository implemented thereon, said apparatus using said natural language-like constructs for specifying said query to said information system by providing means for displaying said conceptual schema utilizing said graphical form of said computer language, drag and drop cursor control means for moving a cursor over said conceptual schema diagram and for selecting a first object and a fact stored in said repository and displayed on said conceptual schema diagram, and fact tree information means for forming a fact tree from said first object and said fact, said first object forming the root node of said fact tree and said fact forming the non-root node of said fact tree, said apparatus further comprising:query mapping means for using said root node as aa first input and returning a first query equivalent to said root node, and for using said non-root node as a second input and returning a second query, said first and said second queries in a computer language appropriate to said database, said query mapping means further including,(a) query variable initialization means, responsive to a call to said query mapping means, for initializing query variables, said query variables comprising Root, WhereClause, FromList and SelecList, JoinTable and JoinColumn, said Root variable initialized to the value of root, and said WhereClause, FromList and SelecList, JoinTable and JoinColumn variables being initialized to a null value, and (b) query build means, responsive to said query initialization means, for receiving said Root, JoinTable and JoinColumn variables, and for building said query, said query build means further including,(i) local build variable initialization means, responsive to invocation of said query build means for initializing local build variables, said local build variables comprising Root, Parent, Nodes and Child(i . . . nodes), Table and Column where said Root variable is set to the value of root, said Parent variable is set to the value of the parent of said root, said Nodes variable is the number of children of said root, Child(i . . . n) are children of said root, said Table variable is the table from said Child(. . . n)'s mapping and said Column is the column for a second noun from said Child(i . . . n)'s mapping, (ii) nodes checking means, responsive to said value of said Nodes variables, for returning to said query mapping means if said nodes checking means determines the value of said Nodes variable to be equal to zero, (iii) parent checking means, responsive to a determination by said nodes checking means that the value of said nodes variable is greater than zero, for checking if the value of said Parent variable is a null value, (iv) first selector adding means, responsive to a determination by said parent checking means that said value of said Parent variable is a null value, for updating said SelectList variable by adding to said SelectList variable the variables Table and Column, said Table variable equal to a table from said node's mapping and said Column variable equal to a column from said node's mapping, where said value of said node is equal to Child(i), (v) join creation means, responsive to a determination by said parent checking means that said value of said Parent variable is other than a null value, for joining a subquery to said query by adding an inner-join to said WhereClause, (vi) iteration counter means for counting iterations, (vii) iteration counter initialization means for initializing said iteration counter means to a value of 1, (viii) iterative node test means for testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means, and returning to said query mapping means if said iterative node testing means determines the value of said Nodes variable to be greater than the value of said iteration counter, (ix) second selector adding means, responsive to a determination by said iterative node test means that said Nodes variable is less than or equal to the value of said iteration counter means, for adding node's Table to said FromList variable and adding said node's table and column to said SelectList variable, where said value of said node is equal to Child(i), and Child(i) is the value of said iteration counter means, (x) recursive query build invoking means for joining queries created for child nodes of said node to said query, (xi) iteration counter incrementing means for incrementing said iteration counter means by a value of 1, and (xii) loop means for returning to said iterative node test means, (c) query variable format means format means for formatting said query variables after said query variables are returned from said query build means, (d) query assembly means for assembling said query from said query variables, and (e) query return means for returning said query mapping means.
 12. The apparatus of claim 5 wherein said first selector adding means further comprises:variable initialization means for setting the value of local variable Node equal to the value of said Child(i) variable; table locating means for setting the value of said Table variable to the table of said Node variable's mapping; column locating means for setting the value of said Column variable to the column for the first noun from said Node variable's mapping; listing means for setting the value of said SelectList variable to the previous value of said SelectList variable added to said Table variable and said Column variable; and selector return means for returning said value of said SelectList variable to said query build means.
 13. The apparatus of claim 5 wherein said second selector adding means further comprises variable initialization means for setting the value of local variable Node equal to the value of said Child(i) variable which is equal to the value of said iteration counter means;table locating means for setting the value of said Table variable to the table of said Node variable's mapping; column locating means for setting the value of said Column variable to the column for the first noun from said Node variable's mapping; first listing means for setting the value of said SelectList variable to the previous value of said SelectList variable added to said Table variable and said Column variable; second listing means for setting the value of said FromList variable to the previous value of said FromList variable added to said Table variable; and selector return means for returning said value of said FromList variable and said SelectList variable to said query build means.
 14. The apparatus of claim 5 wherein said join creation means further comprises:variable initialization means for setting the value of local variable Node equal to the value of said Child(i) variable; table locating means for setting the value of said Table variable to the table of said Node variable's mapping; column locating means for setting the value of said Column variable to the column for the first noun from said Node variable's mapping; join assembly means for assembling said join by setting the value of said WhereClause variable to the value of said WhereClause variable added to said Table variable added to said Column variable added to said Column variable added to said JoinTable variable added to said JoinColumn variable; and join return means for returning said join assembled by said join assembly means to said query build means.
 15. The method of claim 10 wherein said step of updating said SelectList variable further comprises the steps of:setting the value of local variable Node equal to the value of said Child(i) variable; setting the value of said Table variable to the table of said Node variable's mapping; setting the value of said Column variable to the column for the first noun from said Node variable's mapping; setting the value of said SelectList variable to the previous value of said SelectList variable added to said Table variable and said Column variable; and returning said value of said SelectList variable to said step of building said query.
 16. The method of claim 10 wherein said step of joining a subquery to said query further comprises the steps of:setting the value of local variable Node equal to the value of said Child(i) variable; setting the value of said Table variable to the table of said Node variable's mapping; setting the value of said Column variable to the column for the first noun from said Node variable's mapping; assembling said join by setting the value of said WhereClause variable to the value of said WhereClause variable added to said Table variable added to said Column variable added to said JoinTable variable added to said JoinColumn variable; and returning said join to said step of building said query.
 17. The method of claim 10 wherein said step of adding node's table to said FromList variable and adding said node's table and column to said SelectList variable further comprises the steps of:setting the value of local variable Node equal to the value of said Child(i) variable, said Child(i) variable being equal to the value of said iteration counter; setting the value of said Table variable to the table of said Node variable's mapping; setting the value of said Column variable to the column for the first noun from said Node variable's mapping; setting the value of said SelectList variable to the previous value of said SelectList variable added to said Table variable and said Column variable; setting the value of said FromList variable to the previous value of said FromList variable added to said Table variable; and returning said value of said FromList variable and said SelectList variable to said query build means.
 18. A method for generating a query to an information system, said information system having been created using a drag-and-drop information system specification means utilizing a computer language having both textual and graphical forms for translating natural language-like constructs into object-role modeling symbology, said information system specification means further for entering text, utilizing the textual form of said computer language, onto a display device, for parsing said text into at least one of object, fact and constraint into a repository, for forming a conceptual schema representing said information system, and for mapping said conceptual schema to a database, said apparatus implemented on a programmable computer including memory, data entry means, said display means, a graphical user interface, and having said repository implemented thereon, said apparatus using said natural language-like constructs for specifying said query to said information system by providing means for displaying said conceptual schema utilizing said graphical form of said computer language, drag and drop cursor control means for moving a cursor over said conceptual schema diagram and for selecting a first object and a fact stored in said repository and displayed on said conceptual schema diagram, and fact tree formation means for forming a fact tree from said first object and said fact, said first object forming the root node of said fact tree and said fact forming the non-root node of said fact tree, said method further comprising the steps of:(a) initializing query variables, said query variables comprising Root, WhereClause, FromList and SelectList, JoinTable and JoinColumn, said Root variable initialized to the value of root, and said WhereClause, FromList and SelectList, JoinTable and JoinColumn variables being initialized to a null value using query variable initialization means, responsive to said query mapping means, (b) building said query using query build means responsive to said Root, JoinTable and JoinColumn variables, and to said step of initializing query variables, said query build means further comprises the step of,(i) responsive to invocation of said query build means, initializing local build variables comprising Root, Parent, Nodes and Child(i . . . nodes), Table and Column where said Root variable is set to the value of root, said Parent variable is set to the value of the parent of said root, said Nodes variable is the number of children of said root, Child(i . . . n) are children of said root, said Table variable is the table from said Child(i . . . n)'s mapping and said Column is the column for a second noun from said Child(i . . . n)'s mapping, (ii) returning to said step of mapping queries to said database if said Nodes variable is equal to zero, (iii) responsive to a determination by said step of returning to said step of mapping queries that the value of said Nodes variable is greater than zero, checking if the value of said Parent variable is a null value, (iv) responsive to a determination by said step if checking if the value of said Parent variable is a null value that said Parent variable is a null value, updating said SelectList variable by adding to said SelectList variable the variables Table and Column, said Table variable equal to a table from said node's mapping and said Column variable equal to a column from said node's mapping, where said value of said node is equal to Child(i), (v) responsive to a determination by said step of checking if the value of said Parent variable is a null value that said value of said Parent variable is other than a null value, joining a subquery to said query by adding an inner-join to said WhereClause, (vi) initializing an iteration counter means to a value of 1, (vii) counting iterations on said iteration counter means, (viii) testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means, and returning to said step of mapping queries to said database query mapping means if said step of testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means determines the value of said Nodes variable to be greater than the value of said iteration counter, (ix) responsive to a determination by said step of testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means that said Nodes variable is less than or equal to the value of said iteration counter means, adding node's table to said FromList variable and adding said node's table and column to said SelectList variable, where said value of said node is equal to Child(i), and Child(i) is the value of said iteration counter means using second selector adding means, (x) joining queries created for child nodes or said node to said query, (xi) incrementing said iteration counter means by a value of 1, and (xii) returning to said step of testing whether the value of said Nodes variable is less than or equal to the value of said iteration counter means, (c) formatting said query variables after said query variables are returned from said step of building said query, (d) assembling said query from said query variables, and (e) returning to said step of mapping said query. 